Blurring The Legal Line

For seven years, Scott Stokes conducted his own reckless inquiries into the physiological effects of pot.

"I woke up to get high, and I got high to go to bed," recalled the 19-year-old from El Toro, Calif., who broke his marijuana habit after he was arrested two years ago for burglarizing a head shop. "If I didn't have it, I would ... start sweating, and when I'd breathe deep I'd get into these weird breathing patterns.

"People say that marijuana is not addictive, but it's extremely addictive."

Science is less emphatic, but research is beginning to show new evidence that Stokes may be right, in addition to finding other important, sometimes startling insights into how marijuana acts inside the body. A few monumental discoveries in the past decade have given scientists a much clearer grasp of pot's effects on the brain, lungs and other systems, showing how it produces euphoria without creating a risk of fatal overdose.

The discoveries confirm one long-standing hunch about marijuana: It is different than other drugs, acting on its own abundant network of chemical receptors. That knowledge has offered the promise of new drug therapies that might someday help correct faulty memories and poor motor coordination. While some scientists toil on those fronts, others are finding out bad news about the damage pot may cause in the lungs and its slightly suppressive influence on the immune system.

"It's exploding," Dr. Donald Tashkin of the University of California, Los Angeles, said of today's marijuana research. "Now we have the tools. We should be able to learn more and more about [marijuana) in human and animal physiology."

Tashkin's own findings in his work as a research physician are some of the msg wardmost dire for chronic marijuana smokers. For more than a decade, he has been comparing the lungs of pot smokers, cigarette smokers and non-smokers, looking for changes in the airways and cellular damage that may lead to lung cancer.

His pool of volunteers - he began with more than 300 marijuana smokers - undergo regular breathing tests and other procedures, including the removal of lung tissue for study. The preliminary findings show that pot smokers who inhale three or four joints a day suffer from chronic bronchitis as often as cigarette smokers who light up a pack or more a day.

In each case, Tashkin said, the pot smoker and the cigarette smoker also show ominous changes in the linings of the trachea and bronchial tubes. At first, the cilia-covered cells that sweep soot out of the lungs begin to die off, replaced by mucous-producing cells and other tissue cells. In more than half the volunteers who smoke either marijuana or tobacco, the cells eventually became highly abnormal and skinlike in texture, a condition that doctors consider precancerous.

"The cells are disorganized," Tashkin said. "It doesn't mean they're going to turn into cancer, but it's on the way to cancer."

Tashkin, who hopes to publish his findings soon, said the greatest damage is evident in the lungs of those who smoke both marijuana and tobacco, suggesting the effects may add up or even intensify each other.

Marijuana smoke contains many of the same cancer-causing chemicals as cigarette smoke, but a loosely packed, unfiltered joint may deposit four times more tar in the lungs than a cigarette, Tashkin said. In addition, there is evidence that marijuana smoke is more harmful than tobacco smoke to the immune cells in the lungs that attack burgeoning tumors.

Those findings, which he presented at a recent National Institutes of Health symposium on marijuana, are also considered preliminary, he said.

Florida doctors have found similar effects.

Dr. Kasi Sridhar, a specialist at the University of Miami's Sylvester Comprehensive Cancer Center, checked the files of 31 young cancer patients and found that 54 percent had smoked marijuana (all but one also smoked tobacco).

Researchers at the University of South Florida in Tampa found cancer in 27 patients under age 41 who had smoked pot, some of whom had never touched cigarettes.

But most advocates of smoking marijuana as medicine say there is no conclusive proof that smoking pot is harmful. Even if it is, user after user say they are willing to take the risk.

"I would be happy to live so long to get lung cancer" from marijuana, says Irvin Rosenfeld, a Boca Raton stockbroker who smokes pot to ease the pain of a rare disorder. The ailment caused more than 200 tumors on his bones.

Rosenfeld, 44, is one of eight Americans who can legally smoke pot under a federal program - dropped in 1992 - that allowed pot for "compassionate" medical use.

He has smoked 10 to 15 joints a day since 1971. Rosenfeld says his doctors have checked his lungs several times and found no abnormalities.